Bladed wheels of fabricated construction



2 Sheets-Sheet 1 Jan. 20, 1959 E, A. STALKER BLADED WHEELS OF FABRICATEDCONSTRUCTION Filed Oct. 22, 1954 v? INVENTOR.

qm W 5 H E. A. STALKER BLADEID WHEELS OF FABRICATED CONSTRUCTION Jan.20, 1959 2 Sheets-Sheet 2 INVENTOR.

Filed Oct. 22, 1954 speeds of about 400 feet per second or more.

United States Patent BLADED WHEELS OF FABRICATED CONSTRUCTION Edward A.Stalker, Bay City, Mich., assignor to The Stalker Development Company,Bay City, Micln, a corporation of Michigan Application October 22, 1954,Serial No. 464,066

4 Claims. (Cl. 230-134) This invention relates to compressors, turbinesand the like and particularly to the bladed wheels thereof.

An object of this invention is to provide a bladed wheel assembly oflight and economical construction. Another object is to provide a bladedwheel of sheet metal construction.

Other objects will appear from the description, drawings and claims.

The above objects are accomplished by the means illustrated in theaccompanying drawings in which- Fig. l is a fragmentary axial sectionthrough a compressor incorporating a compressor wheel according to thisinvention;

Fig. 2 is a rear axial view of a wheel of the compressor of Fig. lpartly in section;

Fig. 3 is a fragmentary section of a: wheel on line 3-3 in Fig. 2;

Fig. 4 is a fragmentary section on line 4-4 in Fig.

Fig. 5 is a fragmentary section of the disk and rim joints;

Fig. 6 is a fragmentary section through a spacer on line 6-6 in'Fig. 1;

Fig. 7 is a front axial view of a fragment of a spacer;

Fig. 8 shows fragments of two, spacer tubes, in registerihg relation;

Fig. 9 is an axial section at the rim of the first wheel at a throughbolt; and

Fig. 10 is an axial section at the rim of the first wheel and betweenthe through bolts. This invention includes compressor wheels forincreasing the static pressure and density of an elastic fluid. In orderto achieve a significant change in density with an axial flow compressoreach wheel must be operated at a speed high enough to effect asignificant change in. density, that is a change which in magnitude isoutside the usual order of engineering accuracy in industry. Thusmachines are considered to be compressors as distinguished from fans orblowers at tip At such a speed the average change in density along theblade length is about 3% which is just about the common order ofaccuracy of measurement of the density. Such compressors are expectedalso to operate at blade tip speeds close to the velocity of sound. Atsuch speeds the change in pressure may be more than 70% or more than 10pounds per square inch for air inducted at atmospheric pressure.

Since in compressor and turbine wheels there are substantial pressurevariations from front to rear of eachwheel the ratio of the hub radiusto the blade-tip radius is relatively large of a value of the order of0.5 t and preferably greater so that the pressure difference betweenfront and rear sides can be sustained without a return flow at the hubsuch as occurs in a fan. For the same reason the blades are spacedperipherally close together, preferably about one chord length or lessapart.

Commonly half to all the pressure change occurs in the rotor between theleading and trailing edges. To sustain such a change in pressure alongthe rotor passages from leading to trailing edges of the blades the hubrim between adjacent blades and from leading to trailing edges is a fairand continuous surface. Also at all rotative speeds the case must fitclosely about the blade tips which are contoured to the cylindricalsurface of the case along substantially the whole length of the bladechord.

To diffuse the flow between blades to achieve a pressure change the flowshould follow the blade surfaces without eddies. Accordingly the bladesshould have rounded leading edges. They should have sharpened trailingedges to be eificient.

Because of the limited weights of the blades and the rim means the diskof a compressor wheel can have a limited thickness of the order of 0.003times the wheel maximum diameter (tip diameter) or less. Thus ratherlarge disks can have a thickness less than 0.050 of an inch. These wouldbe costly and diflicult to machine. The blades and rim means may havewall thicknesses less than the disk thickness.

It is commonly understood in engineering and industry that sheet metalconstruction is limited to sheets whose planer dimensions are large incomparison to their thicknesses for thicknessesless than about *3 of aninch. Sheets of greater thickness are called plates. (Steel sheet andplate manufacturers list their product of large planer dimensions of dior less as sheets and greater thicknesses as plates.) Sheet metalconstructions are comprised of parts which are cut out from sheetmaterial and require cutting which is limited chiefly to defining thecontours of the part in the plane of the sheet, or to such parts whichare subsequently given another shape by pressing with a die.

Referring now to the drawings thewheel assembly is indicated generallyas 10. It comprises the wheels 12-15, the torque transmitting members orend disks 20 and 21, and the shafts 24 and 26 for mounting the wheelassembly for rotationabout the axes of the shafts. The torquetransmitting members; have portions fixed to the disk by suitablefastening means to be described.

Since the wheels are substantially alike, the front wheel will bedescribed in detail and this will sufiice for the other wheels.

As shown particularly in Figs. 14 the wheel 12 is comprised of the wheeldisk 30, the rim means 32, and the blades 34.

Each blade comprises the blade skin 40 fixed preferably by fused metalto the stem 42 which is made up of the front part 44 and the rear part46. The front part has the flange 48 faying the rim means and fixedthereto pref erably by fused metal while the rear part has the flange 52fixed similarly to the rim means.

The rim means is made of two parts 56 and 58 which are joined over theflanges 60 of the disk 30 and to them by fused metal preferably solder.Rim portions 56 and 58 have flanges 57 and 59 respectively at theirradially inner ends, except on the outer sides of the wheel assembly,which extend axially in overlapping relation with the outer walls andthe fixed vanes 100.

The wheels are supported in series between the end disks 20 and 21 bythe bolts 74 which pass through tubes '76 (Figs. 1, and 68) and thedisks 30. The. tubes are fixed between the outer wall 80 and the innerwalls 82 by fused metal. The tubes 76 are recessed at one end to receivethe tapered end of the adjacent tube 76'. See Figs. 1 and 8. Outer walls80 extend axially between adjacent disks 30 while two inner walls 82 arearranged end to end with The other tubes are formed similarly.

3 abutting flanges 83, such inner and outer walls thus forming spacersbetween disks 30.

The ends of the spacers are formed as illustrated in Figs. 7, .9 ,and10.. A ring 0 fits into each end on the inside surface .of wall 80 towhich it is fixed by fused metal. The radial flange 91 of 9.0 fays aradial flange 92 of the wall 82. The flange 91 has a plurality of holestherein .to pass thebolts 74. The assembly thus provided, including thespacers, the tubes fixed to the outer and inner walls 80 and 82, and theboits 74 passing through end disks 20 and 21, serves to transmit thetorque irornone wheel to the next.

' The outer surface of the wall 80 abuts the flanges of the stator ring100. j

The wheels and the spacers are readily fabricated of vpressingsiandparts of sheet metal, which may be soldered together. This avoidsexpensive machining and leads to a low cost assembly. j

The parts are preferably spot-welded together and sub- :sequentlysoldered in a furnace. Once the dies and tools are produced low costlabor can assemble the parts.

driving the wheel assembly through the bolts and spacers positioned atthe rims of the wheel the disks do not need stiifeners for actingagainst axial loads and the structure has a very low weight.

"It Will thus be clear that the wheel assembly presents the greatadvantages of low Weight and cost.

While Ihave illustrated specific forms of the invention, his to Elieunderstood that variations may be made therein and that I intend toclaim my invention broadly as indicated by the appended claims.

' I claim:

1. In combination in an axial flow rotor assembly compri singat leasttwo rotor wheels spaced axially, each wheel comprising a sheet metaldisk, a plurality of peripherally {spaced axial flow blades carried onsaid disk and projecting outward therefrom with rotor flow passagesbetween said blades for conducting an elastic fluid, said blades beingrotatable with said disk at blade tip speeds greater than .400 feet persecond developing substantial changes in density and pressure in saidfluid flowing through said rotor passages, a rim means of sheet metalconstruction extending between said blades and from front to rearthereof to sustain said changes in pressure and density, said rim meanshaving a radially inward extending iflange, hollow annular spacer meansof sheet metal construction positioned between adjacent said wheels,said spacer means including inner and outer generally cylindrical sheetmetal walls both extending from one wheel disk to the adjacent suchdisk, a torque transmitting rnen1- her having portions thereof adjacentand fixed to said Walls, and fastening means extending in the generalaxial direction into said portions and said wheels and through saidspacer means fixing said wheels and spacer means together for thetransmission of torque from one to the other, said rim flange bearing onsaid spacer means.

2. In combination in an axial flow compressor rotor assembly, at leasttwo rotor wheels in axial tandem relation, each said wheel comprising asheet metal dish, a plurality of peripherally spaced axial flow bladescarried on said disk and projecting outward therefrom with rotor flowpassage between said blades for conducting an elastic fluid, said bladesbeing rotatable with said disk at blade tip speeds greater than 400 feetper second developing substantial changes in density and pressure insaid fluid flowing through said rotor passages and developingcentrifugal loads at the inner ends of said blades, said disk having athickness less than 0.003 times the maximum.

diameter of said wheel for sustaining said centrifugal loads, a rimmeans of sheet metal construction extending between said blades and fromfront to rear thereof to sustain said changes in pressure and density,said rim means having a radially inward extending flange, hollow annularspacer means of sheet metal construction positioned between adjacentsaid wheels, said spacer means including generally cylindrical sheetmetal walls substantially coextensive with each other and extendingbetween adjacent said wheel disks, a torque transmitting member havingportions thereof adjacent to said rim means, and bolt means extending inthe general axial direction into said portions and said wheels andthrough said spacer means fixing said wheels and spacer together for thetrans mission of torque from one to the other, said rim flange bearingon said spacer means.

3. in combination in an axial flow compressor rotor assembly, at leasttwo rotor wheels in axial tandem relation, each said wheel comprising asheet metal disk, a plurality of peripherally spaced axial flow bladescarried on said disk and projecting outward therefrom with rotor flowpassage between said blades for conducting an elastic fluid, said bladesbeing rotatable with said disk at blade tip speeds greater than 400 feetper second developing substantial changes in density and pressure insaid fluid flowing through said rotor passages, said blades being ofhollow sheet metal construction of light weight developing limitedcentrifugal loads at the inner ends of said blades, said disk having athickness less than 0.003 times the maximum diameter of said wheel forsustaining said centrifugal loads, a rim means of sheet metalconstruction extending between said blades and from front to rearthereof to sustain said changes in pressure and density, said rim meanshaving a radially inward extending flange, each said blade including ablade skin and a stern, said stern having a flange at the side thereofextending axially to said flange of said rim means and being fixedthereto for the support thereof, hollow annular spacer means of sheetmetal construction positioned between adjacent said wheels, said spacermeans including generally cylindrical sheet metal walls substantiallycoextensive with each other and with the space between adjacent wheel.disks, torque transmitting members in the form of tubes positionedbetween and secured to both said walls adjacent to said rim means, andbolt means extending in the general axial direction through said tubesand said wheels fixing said wheels and spacer means together for thetransmission of torque from one to the other.

4. in combination in an axial flow rotor assembly, a rotor wheelcomprising a sheet metal disk, a plurality of peripherally spacedaxially flow blades each including a blade skin and an internal stemextending radially inwardly of said skin, means for fixing said stems tosaid disk in peripherally spaced relation thereon with said bladesprojecting outwardly therefrom defining flow passages between the bladesfor conducting an elastic fluid, a rim means of sheet metal constructionextending between said blades and from front to rear thereof to sustainchanges inpressure and density, said rim means having a radiallyinwardly extending flange faying the inner portion of said stern means,and means for bonding the flange of saidrim means to said stem portionsto fix said rim means in assembled position thereon.

References Cited in the file of this patent

